The U.S. Agricultural Research Service is awaiting permission to release two foreign fungi to kill off tumbleweed. Tumbleweed is iconically associated with the American West, but it is more accurately called Russian thistle. It was brought to America in the 1870’s by Russian immigrants as a contaminant in flaxseed. It has since spread over 100 million acres causing trouble wherever it goes.
Tumbleweed displaces crops and native plants. It dries out soil and aids in the spread of wildfires. It triggers allergies and impacts highway safety. It, along with other exotic plant pests, costs the American economy an estimated $34 billion a year. There have been other attempts to deal with the tumbleweed problem. Bio-control using natural predator insects was tried and failed.
In the late 1990’s researches discovered two fungi native to the Eurasian steppes that cause disease in tumbleweed. There has been over a decade of research done on the safety of using those fungi to combat tumbleweed here without damaging other native plant life. Safety tests were conducted in a bio-safe level 3 greenhouse (BL3-P). BL3-P facilities are designed to prevent the accidental release of plants, plant pathogens or other organisms that have a recognized potential for significantly detrimental impact on the environment. Even so, it is not possible to test the pathogen on every plant. Instead, researchers rely on a mathematical model called BLUPs—Best Linear Unbiased Predictors.
After about a decade of research—plus more work, done by predecessors—he thinks he’s got an answer: Two fungi species that hail from the Eurasian steppes to which tumbleweed is native. He and his colleagues have submitted applications to release these exotic fungi on willing U.S. farmers’ lands. Now they’re just waiting for an answer.
“I’m very optimistic on its ability to control tumbleweed. We just need to get it released,” Berner tells Popular Science. “We have lots of evidence on it that it’s safe and effective.”
The fungi cause the tumbleweed leaves to shrivel and drop off or cause cankers on the stem interfering with plant nourishment.
If the fungi are approved for use, let’s hope BLUPs doesn’t turn to OOPs.